Green is a signal, not a guarantee

A test can pass for the wrong reason. The assertion might be too broad, the fixture too forgiving, or the environment too different from production. A green build tells you that the checks you wrote passed under the conditions you provided. It does not tell you that every important risk has been covered.

Start with the risk

Before adding another test, write down the failure you are trying to prevent. A checkout that charges twice needs different evidence from a button with the wrong label. Rank those risks by customer impact and likelihood, then choose the cheapest reliable check for each one.

Make failure informative

A useful test should help the next person understand what broke. Assert the behavior that matters, name the scenario clearly, and include relevant context in the failure output. When a test fails, someone should be able to decide what to investigate without replaying the entire suite.

The goal is not a wall of green. The goal is confidence you can explain.

Try breaking your own assumptions

Change an expected value. Remove a permission check in a safe local branch. Return an empty response from a dependency. If the relevant tests still pass, you have found a gap in the evidence, not a reason to celebrate.

A better conversation at release time

Ask which risks the suite covers, which it cannot cover, and what changed since the last release. Pair automated checks with focused exploratory testing. Confidence comes from combining evidence, not counting assertions.